As operating frequencies of high speed interfaces increase, the input parasitic capacitance of the high frequency circuit elements must scale inversely with the increase in frequency to maintain an acceptable return loss and to avoid deteriorating insertion loss. In fact, certain industry standards mandate specific levels of return loss and insertion loss that may be difficult to maintain with standard circuit element and transmission line design. Furthermore, it may be difficult to sufficiently miniaturize input structures, such as electro-static discharge protection diodes and their associated parasitic capacitance, while maintaining sufficient electro-static discharge protection.
On-die spiral inductors have been used to compensate for parasitic input capacitance. Unfortunately, spiral inductors are relatively large in size, and the space they occupy on dies significantly hinders the design of sufficiently small circuit elements. Furthermore, other techniques for improving return loss, such as microwave matching techniques, may only be effective over a narrow frequency band.